const array1 = [1, 2, 3, 4];

const reducer = (accumulator, currentValue) => accumulator + currentValue;

​

// 1 + 2 + 3 + 4

console.log(array1.reduce(reducer));

// expected output: 10

​

// 5 + 1 + 2 + 3 + 4

console.log(array1.reduce(reducer, 5));

// expected output: 15

var array = [36, 25, 6, 15];

​

array.reduce(function(accumulator, currentValue) {

  return accumulator + currentValue;

}, 0); // 36 + 25 + 6 + 15 = 82

const arr = [1, 2, 3]

const result = arr.reduce((acc, curr) => acc + curr, 0)

// 1 + 2 + 3 = 6

console.log(result)

let array = [36, 25, 6, 15];

array.reduce((acc, curr) => acc + curr, 0)

// 36 + 25 + 6 + 15 = 82

c7208648b19086ffaef0da34bbb912f6

​

const arr = [3, 5, 4, 11, 7, 22];

​

arr.reduce((previousValue, currentValue) => {

    return previousValue + currentValue;  // <--- 3 + 5 + 4 + 11 + 7 + 22 = 52

}, 0) 

var depthArray = [1, 2, [3, 4], 5, 6, [7, 8, 9]];

​

depthArray.reduce(function(flatOutput, depthItem) {

    return flatOutput.concat(depthItem);

}, []);

​

=> [1, 2, 3, 4, 5, 6, 7, 8, 9];

​

​

// --------------

const prices = [100, 200, 300, 400, 500];

const total = prices.reduce((total, cur) => {return total + cur} )

//  init value = 0 => total = 1500;

​

​

// --------------

const prices = [100, 200, 300, 400, 500];

const total = prices.reduce(function (total, cur) => {

                   return total + cur

                }, 1 )

// init value = 1 => so when plus all numnber will be result => 1501;

​

// --------------

const prices = [100, 200, 300, 400, 500];

const total = prices.reduce((total, cur) => total + cur )

// 1500;

​

const sum = array.reduce((accumulator, element) => {

  return accumulator + element;

}, 0);

// define a reusable function

const calculateSum = (arr) => {

    return arr.reduce((total, current) => {

        return total + current;

    }, 0);

}

​

// try it

console.log(calculateSum([1, 2, 3, 4, 5]));

const list = [1, 2, 3, 4, 5];

console.log(list.reduce((number, nextNumber) => number + nextNumber));

// --> 15